Also: The search for an AIDS vaccine. And fossil remains of a small dinosaur show similarities to Tyrannosaurus rex. Transcript of radio broadcast:

VOICE
ONE:

This
is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty.

VOICE
TWO:

And I'm Faith Lapidus. This week, we will tell about an experimental
vaccine against the disease AIDS. We
also will tell about a newly found hiding place for harmful bacteria. And we will tell about a discovery that could
change scientific beliefs about dinosaurs.

(MUSIC)

VOICE
ONE:

Researchers
say they still have much work to do on a vaccine against the virus that causes
AIDS. But the first reports of some
success have raised hopes. Scientists
say an experimental vaccine reduced the risk of infection in human beings by
thirty-one percent and was safe.

The study was designed
to test for two abilities. One was the
ability of the vaccine to prevent infections from the human immunodeficiency virus,
better known as H.I.V. The other was the
vaccine's ability to reduce the amount of virus in the blood of people who
became infected during the study.

VOICE TWO:

Volunteers
received vaccinations over a period of six months. They were tested for H.I.V. for an additional
three years. The testing began six years
ago. It was the largest AIDS vaccine
study yet. It involved more than sixteen
thousand adults in Thailand. Half
received the vaccine. The other half
received a placebo, or harmless substance. The volunteers did not know which
they were getting.

Seventy-four
people in the placebo group became infected during the study. The researchers say that was compared with
only fifty-one of those who received the vaccine.

VOICE ONE:

Doctor
Supachai Rerks-Ngarm led the study for Thailand's Ministry of Public Health. The United States government paid for the
study. Doctor Anthony Fauci of the
National Institutes of Health called the findings, an important step forward. He said it represents the first time an
investigational H.I.V. vaccine has shown some ability to prevent infection. But he also said additional research is
needed to better understand how the vaccine reduced the risk in those
individuals.

The
vaccine did not lower the amount of virus in the blood of volunteers who became
infected during the study.

VOICE TWO:

The study was based on versions of H.I.V. commonly
found in Thailand. The volunteers
received a combination of two vaccines. The first, or prime, vaccine came from Sanofi Pasteur. The second, or booster, vaccine was developed
by another company, VaxGen. The non-profit
group Global Solutions for Infectious Diseases now has rights to it.

Neither
vaccine had been successful by itself when tested earlier. More detailed results of the study are
expected to be presented at a conference in France later this month.

(MUSIC)

VOICE
ONE:

We
all have heard about harmful bacteria hiding in the home. Studies have discovered evidence of harmful
bacteria in toilets, on surfaces where food is prepared, even on home telephones.

Recently, American researchers
found harmful bacteria in a place most of us would never suspect. They found that the bathroom showerheads
people use to wash up may be covering us with more than water.

VOICE
TWO:

The
researchers used a molecular genetics test to examine fifty showerheads from
nine American cities. Those showerheads
came from homes and public places in Colorado, Illinois, New York, North Dakota
and Tennessee.

Thirty percent of the
devices had high levels of Mycobacterium avium, an organism linked to lung
disease. The researchers say the
bacteria were grouped together in a thin, but sticky area of cells on the
inside of showerheads. They say the
levels of Mycobacterium avium were one hundred times higher than that of normal
household water. And, showerheads made
of plastic seemed to have higher bacteria levels than metal ones.

One
of the showerheads was cleaned with a bleach solution in an effort to destroy
the bacteria. Bleach is often used as a
whitening agent when washing clothes. Tests
showed that instead of killing the bacteria, the bleach actually caused the
bacteria levels to increase.

VOICE
ONE:

A
report about the study appeared last month in the Proceedings of the National
Academy of Sciences.

The
lead writer of the report was Norman Pace of the University of Colorado at
Boulder. Professor Pace has a warning
for people who let water hit their face when they first turn on the shower. He says they probably are getting a full face
of the unhealthy bacteria. He says the
bacteria can also float around in the air and be easily pulled into the
lungs.

The
professor says earlier research at National Jewish Hospital in Denver supports
this theory. The research suggested that
increases in pulmonary infections in the United States may be linked to people
taking more showers than traditional baths.

Signs
of pulmonary disease caused by Mycobacterium avium can include shortness of
breath, a continual dry cough, and feelings of tiredness or weakness.

The
researchers say showers may not be big a problem for healthy people. But, they warn that persons with weakened defenses
for fighting disease are at greater risk. This includes pregnant women, older adults and people with other
diseases.

(MUSIC)

VOICE
TWO:

Many young
children can describe the well-known prehistoric dinosaur, Tyrannosaurus rex. T. rex had a big head, long legs
and small arms. Its teeth filled a
fierce-looking mouth that was heavy with muscles.

Now,
try to imagine a dinosaur that looked like T. rex. But the creature you are imagining is only
one-hundredth of T. rex's size. This
describes Raptorex Kriegsteini -- a distant relative of T. rex. Researchers say Raptorex might have looked
like a toy version of the huge creature.

VOICE ONE:

Raptorex was not a T. rex. Instead, it belonged to a tyrannosaurid
species that lived many millions of years before its T. Rex relative. An examination of Raptorex and its meaning
to dinosaur development appeared recently on the Internet version of "Science"
magazine.

The small dinosaur is thought to have lived about one
hundred twenty-five million years ago. T. Rex lived between sixty-five and eighty-five million years ago.

Researcher
Stephen Brusatte says scientists have believed that the physical qualities of
Tyrannosaurus developed because of its large body. But he notes similar qualities in the smaller
Raptorex.

For
example, the small arms on T. rex did not develop as the creature got
bigger. Instead, such arms were also
present earlier. The researcher says
traditional beliefs about Tyrannosaurus' development were too simple -- or
wrong.

VOICE TWO:

Stephen Brusatte is a doctoral candidate at Columbia
University in New York. He works with
the city's American Museum of Natural History. He helped write about Raptorex Kriegsteini with Paul Sereno of the
University of Chicago, the lead writer and researcher.

Professor Sereno says Raptorex Kriegsteini was probably
just as effective at killing as T. rex. He notes that Raptorex's body was about two and seven-tenths meters long. The creature weighed only sixty-eight
kilograms, about the same as many people. The professor said it probably died at an early age, living only about
five or six years.

VOICE ONE:

The
head of Raptorex Kriegsteini shows evidence of a well-developed olfactory
system. The researchers suspect Raptorex
had a strong sense of smell. The
professor says the body design of the creature made it a kind of jaw on
legs. It appeared to be a successful
finder and killer of other animals.

Professor
Sereno received fossilized remains of the creature three years ago from a
private collector in the American state of Massachusetts. The Raptorex Kriegsteini reportedly was
discovered inside a single piece of rock in the Inner Mongolia area of
China. The fossil was removed from China
under mysterious conditions. It had
reached the collector, Henry Kriegstein, through sales.

Doctor
Kriegstein later sent it to an expert who recognized its importance. The doctor then contacted Professor Sereno. Doctor Kriegstein named the fossil to honor
his parents and donated it to science. Paul Sereno said the fossil will be returned to China and put in a
museum when the scientists have finished their studies.

(MUSIC)

VOICE TWO:

This
SCIENCE IN THE NEWS was written by June Simms, Jerilyn Watson and Caty
Weaver. Our producer was Brianna
Blake. I'm Faith Lapidus.

VOICE ONE:

And,
I'm Bob Doughty. Join us again next week for more news about science in
Special English on the Voice of America.